Updating Blender and keeping settings
If you are talking about user preferences and startup file, you can access your old blender directory:
go to the appdata/roaming folder (type Windows Key+R and then %appdata%) go to the blender foundation folder. Then 2.78 => and open userpref or startup .blend depending on what you want to get in the new version. Then save user prefs (Ctrl+Alt+U and save user prefs) and save the startup file (Ctrl+U)

Or alternatively copy these files into 2.78c\config, but I'm not sure if this will work